Our goal is to produce transgenic mice deficient in the murine prostaglandin receptor EP1. We will then study the effects of the nullification of this receptor on inflammatory pathways. The murine EP1 receptor is comprised of 405 amino acids and has seven transmembrane spanning domains common to all G-proteincoupled receptors. Binding of prostaglandin-E2 to the membrane of cells possessing the EP1 receptor causes a rapid increase in intracellular calcium. EP1 is expressed abundantly in kidney and to a lesser amount in lung. To generate the transgenic mice, a murine genomic library was screened using a radiolabeled RT-PCR generated EP1 cDNA probe. DNA from the phage subclones was recovered and restricted with Not-1 to isolate the genomic insert from the rest of the phage DNA. The genomic insert was then cloned into a modified bluescript vector. This recombinant plasmid will be used to make a "knock-out" construct which will be electroporated into ES cells. Cells in which gene targeting occurs by homologous recombination will be selected for and injected into blastocysts to form chimeric mice.